BMW 3: Flat Tire Monitor FTM

Concept

The system detects tire inflation pressure loss on the basis of rotation speed differences between the individual wheels while driving.

In the event of a tire inflation pressure loss, the diameter and therefore the rotational speed of the corresponding wheel changes. The difference will be detected and reported as a flat tire.

The system does not measure the actual inflation pressure in the tires.

Functional requirements

The following conditions must be met for the system; otherwise, reliable flagging of a loss of tire inflation pressure is not assured:

• After a tire or wheel replacement, an initialization was performed with the correct tire inflation pressure.
• After the tire pressure was adjusted to a new value, an initialization was performed.

Status display

The current status of the flat tire monitor can be displayed, for instance whether the RPA is active.

Via iDrive:

1. "CAR".

2. "Vehicle status".

3. "Flat Tire Monitor".

The status is displayed.

Initialization required

An initialization must be performed in the following situations:

• After the tire inflation pressure has been adjusted.
• After a tire or wheel replacement.

Performing initialization

When initializing, the set tire inflation pressures serve as reference values in order to detect a flat tire. Initialization is started by confirming the tire inflation pressures.

Do not initialize the system when driving with snow chains.

Via iDrive:

1. "CAR".

2. "Vehicle status".

3. "Flat Tire Monitor".

4. Switch on drive-ready state and do not drive off.

5. Start the initialization with: "Perform reset".

6. Drive away.

The initialization is completed while driving, which can be interrupted at any time.

The initialization automatically continues when driving resumes.

Messages

General information

When a flat tire is indicated, DSC Dynamic Stability Control is switched on, if needed.

Safety information

Warning A damaged regular tire with low or missing tire inflation pressure impacts handling, such as steering and braking response. Run-flat tires can maintain limited stability. There is a risk of accident. Do not continue driving if the vehicle is equipped with normal tires. Follow the information on run-flat tires and continued driving with these tires.

Indication of a flat tire

A yellow warning light is illuminated in the instrument cluster.

In addition, a symbol with a Check Control message appears on the Control Display.

There is a flat tire or a major loss in tire inflation pressure.

Measure

1. Reduce your speed and stop cautiously.

Avoid sudden braking and steering maneuvers.

2. Check whether the vehicle is fitted with normal tires or run-flat tires.

Run-flat tires are labeled with a circular symbol containing the letters RSC marked on the tire's sidewall.

Actions in the event of a flat tire

Normal tires

1. Identify the damaged tire.

To do this, check the tire inflation pressure in all four tires, for instance using the tire pressure gage of a flat tire kit.

If the tire inflation pressure in all four tires is correct, the Flat Tire Monitor may not have been initialized. In this case, initialize the system.

If identification of flat tire damage is not possible, please contact a dealer's service center or another qualified service center or repair shop.

2. Repair the flat tire, e.g., with a flat tire kit or by changing the wheel.

Run-flat tires

Safety information

Warning Your vehicle handles differently with a run-flat tire with no or low inflation pressure; for instance, your lane stability when braking is reduced, braking distances are longer and the self-steering properties will change. There is a risk of accident. Drive moderately and do not exceed a speed of 50 mph/80 km/h.

Maximum speed

You may continue driving with a damaged tire at speeds up to 50 mph/80 km/h.

Continued driving with a flat tire

Follow the following when continuing to drive with a damaged tire:

1. Avoid sudden braking and steering maneuvers.

2. Do not exceed a speed of 50 mph/80 km/h.

3. Check the tire inflation pressure in all four tires at the next opportunity.

If the tire inflation pressure in all four tires is correct, the Flat Tire Monitor may not have been initialized. In this case, initialize the system.

Possible driving range with a depressurized tire

The distance for which it may be possible to drive safely varies depending on how the vehicle is loaded and used, e.g., speed, road conditions, external temperature. The driving range may be less but may also be more if an economical driving style is used.

If the vehicle is loaded with an average weight and used under favorable conditions, the distance for which it may be safe to drive may be up to 50 miles/80 km.

Vehicle handling with damaged tires

Vehicles driven with a damaged tire will handle differently, potentially leading to conditions such as the following:

• Greater likelihood of swerving off course.
• Longer braking distances.
• Changed self-steering properties.

Modify your driving style. Avoid abrupt steering maneuvers or driving over obstacles, for instance curbs or potholes.

Final tire failure

Vibrations or loud noises while driving can indicate the final failure of a tire.

Reduce speed and stop; otherwise, pieces of the tire could come loose and cause an accident.

Do not continue driving. Contact a dealer's service center or another qualified service center or repair shop.

System limits

The system could be delayed or malfunction in the following situations:

• A natural, even tire inflation pressure loss in all four tires will not be recognized. Therefore, check the tire inflation pressure regularly.
• Sudden serious tire damage caused by external circumstances cannot be recognized in advance.
• When the system has not been initialized.
• When driving on a snowy or slippery road surface.
• Sporty driving style: spinning traction wheels, high lateral acceleration (drifting).
• When driving with snow chains.

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